There’s a struggle going on inside the brain of David Eagleman for the soul of David Eagleman.

That is, there might be such a struggle if Eagleman’s brain believed that Eagleman had a soul, which he is not sure about. In fact, Eagleman’s brain is not completely sure that there is an Eagleman-beyond-Eagleman’s-brain at all, with or without a soul, whatever that term might mean.

Welcome to the world of “possibilian” neuroscientist-writer David Eagleman, to life in the space between what-is and what-if, between the facts we think we know and the fictions that illuminate what we don’t know.

Eagleman-the-scientist would love to rev up his high-tech neuroimaging machines to answer the enduring questions about the brain and the mind, the body and the soul. But Eagleman-the-writer knows that those machines aren’t going to answer those questions.

So, while he reports on what-is in scientific journals, his brain and mind run free pondering the what-ifs, as he did in the 2009 book Sum: Forty Tales from the Afterlives, a playful series of short philosophical imaginings of life beyond death. And, if things work out the way Eagleman hopes, someday he’ll get a shot at a larger stage where he can fulfill his dream of becoming the Carl Sagan of the brain, explaining the billions and billions of neurons in our head to a curious public.

Anything’s possible

Though they might seem different, Eagleman’s scientific and literary lives really are part of the same creative endeavor aimed at deepening our understanding of a complex world we can never really come close to understanding. In the spiritual realm, that leads Eagleman to reject not only conventional religion but also the label of agnostic or atheist. In their place, he has coined the term possibilian: those who “celebrate the vastness of our ignorance, are unwilling to commit to any particular made-up story, and take pleasure in entertaining multiple hypotheses.”

Since scientists mostly talk about what they know, Eagleman’s emphasis on our ignorance may seem strange. So, it’s time for an analogy. Eagleman likes analogies.

The work of science is like building a pier out into the ocean, he says. We excitedly add on to the pier little by little, but then we look around and say, “Wait a minute, I’m at the end of the pier but there’s a lot more out there.” The ocean of what we don’t know always dwarfs what we do know, he emphasizes. “During our lifetimes, we will get further on that pier. We’ll understand more at the end of our lives than we do now, but it ain’t going to cover the ocean.”

Settling in at his office at the Baylor College of Medicine in Houston, Eagleman swivels 180 degrees in his chair, his foot pushing off the various pieces of office furniture to propel him around like a kind of wind-up machine, the verbal velocity moving between fast and faster depending on his fascination with a particular idea. Those ideas can range from the latest experiments he’s running in the five fMRI (functional Magnetic Resonance Imaging) machines down the hall, to age-old philosophical questions about free will and implications for the legal system, to those speculations about an afterlife.

His first book, the co-authored Wednesday is Indigo Blue: Discovering the Brain of Synesthesia, analyzed the phenomenon of synesthesia (a condition in which one sense, such as sight, is simultaneously perceived by another sense, such as hearing – “hearing a color,” for example). One reviewer recommended the book for those with “a passion for neurology’s wild territory,” which Eagleman is exploring further for a general audience in his third book, the forthcoming Dethronement: The Secret Life of the Unconscious Brain. His central project in that book, and all his scientific work, is to understand how the human brain constructs reality.

In between those two books came Sum, a surprising success in the United States and Britain that is now out in paperback. It also spawned a theatrical adaptation staged at the Sydney Opera House in Australia with an original score written and performed by avant-garde musician-producer Brian Eno. The book’s speculative musings have captured the imagination of a small but lively group of people who claim the possibilian label, leading Eagleman to begin writing Why I’m a Possibilian to flesh out the ideas.

Taking seriously the old saying “the absence of proof isn’t the proof of absence,” Eagleman recognizes that people who don’t believe in God (at least not in God defined as a supernatural force or entity) can never say with certainty what doesn’t exist. So, the difference between agnostic and atheist is typically a matter of attitude, and such is the case with adding possibilian to the mix. Eagleman is not trying to support or rule out any particular claim but simply suggesting that it’s healthy to imagine possibilities.

What if there is an afterlife where we relive all our experiences but shuffled into a new order? What if in an afterlife we confront all the possible versions of our self that could have been? What if we experience death in stages: when the body stops functioning, when we’re buried, and the moment when your name is spoken by another for the last time? Sum offers 40 such what-ifs. [For a video trailer of the book, go to http://www.youtube.com/watch?v=zXQpZK5pp0E.]

The stories aren’t meant as serious proposals about what an afterlife may be, and are really just a vehicle for Eagleman’s ruminations on the vexing philosophical questions we face in life. When we talked in his Houston office, Eagleman was finishing the last chapter of Dethronement to send off to the publisher, and those questions were on his mind. One of the most basic concerns the mind: Is our consciousness the product of anything beyond the material realm? Is there anything beyond the physical brain? If there is something beyond, is that what we should call the mind? What does all this mean for the concept of the soul?

Pinning down consciousness

Eagleman acknowledged that in labs such as his, neuroscientists work under the assumption that “you are nothing but your brain,” and many scientists and philosophers come close to suggesting that this is not an assumption but a fact. Eagleman refers to this as the “hardcore” reductionist/materialist view – reducing the mental to the material, reducing the mind to the physical brain. That could be the case, he says, but it makes him nervous.

His first hesitation is common; no one could really look at humans as “just a bunch of atoms, or just a bunch of neurons” because of the concept of emergent properties. Eagleman explains: “If you took any piece of an airplane, that piece of metal does not have the property of flight. It’s only when you put it together in exactly the right way that you get something out of it.” The key is the interaction among the components, the properties that emerge from that specific interaction that the individual components don’t have alone.

Here’s a classic example: At room temperature, hydrogen and oxygen are gases. Combine one oxygen and two hydrogen atoms and you get water. Liquidity is an emergent property, which no chemist could have predicted by analyzing the individual atoms. The same can be said of us – we are made up of material components, but what is interesting about humans is not those components but the emergent properties. Consciousness couldn’t be predicted from a list of the elements that make up each one of us.

Eagleman’s second hesitation is more intriguing. We shouldn’t presume, he says, that we know about all the pieces that make us up or all the forces that structure the world in which we operate. Enter the possibilian.

“Almost certainly, we’re missing giant pieces,” he says, just as previous generations were missing a big piece of the puzzle when they attempted to understand the world without the concept of gravity. “We’re in that situation now, and the reason we know we’re in that situation is because for the most fundamental questions we have, like consciousness, we not only don’t know the answer but we don’t even know what the answer could look like.”

The question of consciousness? “How do you put together a bunch of physical pieces and parts, and get private subjective experience out of that? How do you get the taste of feta cheese or the redness of red or the feeling of pain?”

Neuroscience labs are busy mapping neural circuits – the signals within the brain, and between the brain and the rest of the body – but Eagleman emphasizes “that’s just mechanical stuff, and every single discovery in every neuroscience lab is just mechanical stuff.” He’s happy to tell anyone who will listen about the amazing stuff that neuroscience has figured out, but he doesn’t want to get lost in that.

“We’re stuck with this very deep problem, this 800-pound gorilla: If it’s all just mechanical stuff everywhere we look and if every part of the brain is connected to, and driven by, other parts of the brain, then where’s consciousness?” For most folks, the answer might be, “Well, it’s in my mind.” But that begs the question of what we mean by mind, beyond the physical brain. What is a mind? (A quick quiz: Your brain weighs about 3 pounds. How much does your mind weigh?)

Long before fMRI machines, philosophers have been debating these questions. David Sosa, a professor and philosophy department chair at the University of Texas at Austin, says the materialists dominate the field these days, though he remains a dualist (a type of theory that argues the mind and the brain, the mental and the physical, are different kinds of thing). Sosa is respectful of the work of neuroscientists and agrees philosophers should be engaging their findings, but he’s unwilling to rush to judgment.

Eagleman shares that caution. He has no glib response about the question of consciousness and says there’s not even a clear way to frame questions about private subjective experience – “there’s no equation that can give us the taste of feta cheese,” he says.

That’s why Eagleman, a hardcore neuroscientist who loves the “stuff” coming out of his lab as much as conventional religious believers love the “stuff” in their holy books, isn’t a hardcore materialist. But what could the missing pieces be? Time for another analogy.

Imagine folks with no exposure to modern gadgets find a radio. They hear a human voice coming out, yet there’s no one speaking. They fiddle with the radio, remove the back cover, pull on a wire, and observe that the voice stops. They reconnect the wire, and the voice is back. They touch other parts and the voice changes. Not knowing about the electromagnetic spectrum, these tinkerers would be tempted to assume the voice is coming from the radio itself.

Back to emergent properties. It might be tempting to conclude that the voice is an emergent property of the radio, of the way the parts and pieces are arranged, but that would miss the invisible radio waves. “The physical integrity of the radio is necessary for its proper functioning, but it’s not about the physical thing. That’s just a receiver for things coming from elsewhere,” Eagleman says.

It’s plausible, he concludes, that we could be waiting for the neuroscience equivalent of discovering the law of gravitation, waiting to discover “whole new – I don’t even know what to call them – forces or dimensions or whatever. A hundred years from now people might say, ‘those poor assholes in the 21st century were trying to solve the consciousness problem and they didn’t even know about force X.’”

Eagleman is quick to make it clear he’s not saying there’s a force X; he doesn’t want to be lumped in with the folks peddling New Age flakiness. He just wants to keep an open mind, which is what he thinks science is all about – extend the pier but don’t forget about the vastness of the ocean, expand what we know but remember that what we know is dwarfed by what we don’t know.

Scientific story-tellers and lock-pickers

At moments like this, the scientific and the literary Eagleman are most clearly one. Human beings, including scientists, he emphasizes, are storytellers. He believes scientists tell some of the best stories humans have come up with to explain how the world works. But the way that the “facts” of the science of one era are replaced by new discoveries should remind us that science is always just telling stories. The earth is pushed out of the center of the universe, Newtonian physics gets nudged by quantum mechanics – science marches on, with lots of “facts” left by the side of the road to rust.

Throw a stone into any contemporary university English department and you’ll hit at least one postmodern literary theorist who will talk about science as narrative, but it’s rare to hear it from a scientist who is as committed to the scientific project as Eagleman. Here’s someone running a lab with five high-test fMRI machines, 16 employees, and a half-million dollar-a-year budget. And it’s all just stories?

“I don’t want to say ‘just stories.’ These are the best stories we have on the planet,” he asserts, the stories that cure disease and make space travel possible. “I’m just saying that they are narratives that can change. Science is a tremendously successful pursuit, but there’s a lot of wiggle room.”

The awareness that there is always potentially a game-changing discovery around the corner is, for Eagleman, the allure of science. “I don’t think people would want to go into science unless they thought there was something big to be discovered. You go in because you think, ‘I want to kick over the whole fucking chessboard.’ That’s what makes a good scientist.”

Growing up in Albuquerque, NM, with a psychiatrist father and biologist mother who both loved books, Eagleman was exposed to lots of discussion about what makes good science and good literature. When he went off to college to major in literature at Rice University in Houston, he dabbled in space physics and engineering but avoided biology; his last biology class had been in the 10th grade, at which time he pronounced the subject “gross.” But late in his undergraduate career he found himself drawn to questions about the brain, and once he started reading he was hooked.

After doctoral work at the highly rated program in neuroscience at Baylor College of Medicine, he spent five years in San Diego in a fellowship at the Salk Institute before taking a faculty job in the University of Texas-Houston Health Science Center. Baylor lured him back three years ago. With funding from the National Institutes of Health and a few smaller grants, he pays for a lab in which undergraduates, graduate students, and regular staff members work out of a half-dozen cubicles. Conversations about work, along with various pieces of hardware used in experiments, spill over to the office’s combined conference table/lunch room. The whiteboard walls (which are actually a light blue) sport a kind of scientific graffiti – ideas for projects, questions about projects, lists of things to be done on projects – that reflects the serious but anarchic spirit of the lab.

Eagleman brings a possibilian sensibility to the lab. Over lunch, staff members reflected on that sense of openness. Research assistant Elyse Aurbach, a Rice University grad who is applying to graduate schools in neuroscience, calls Eagleman and the lab “genuinely scientific” – any idea that is intriguing is worth discussing, no matter who proposes it, and the emphasis is on innovation and collaboration. Don Vaughn was a high school student in San Diego when he met Eagleman at his school’s Science Day. After graduating from Stanford and working in investment banking for a summer (“Banking really wasn’t for me,” says the mohawk-coiffed Vaughn), he bugged Eagleman to give him a job. Now he’s working on a new study on empathetic responses in the brain as he ponders graduate school. Greg Bohuslav is a University of Houston undergrad who loves the nimbleness of the lab. When people have ideas, Eagleman will let them run a quick experiment to test it, most of which fail. To do that work without big grants, Bohuslav likes to help design devices used in experiments. “We build a stimulator (device that shoots puffs of air to stimulate the skin) for $2,500 that would have cost $35,000 to buy,” he says proudly. “There’s a value placed on ingenuity here, kind of like lock-pickers.”

Although it’s more freewheeling than most, the lab produces conventional science. For all the talk of humans’ intellectual limits – of small piers and vast oceans, of upended chessboards – there’s no doubt that Eagleman believes deeply in science. In theory, he’ll consider possibilities. But in practice, he bets on science.

Back to the radio analogy. Even if there is a force yet to be discovered that would change the way we think about consciousness, as understanding radio waves would change the understanding of a radio, Eagleman points out that we have to know how the radio works. And he wants to know how the brain works. “Understanding the machinery is not a bad pursuit at all,” he says. “It doesn’t rob the myste…, doesn’t rob the awe from everything.”

Why does he stop himself from saying “mystery”? Why replace it with “awe”?

Eagleman explains that Frances Crick, the Nobel laureate biologist whom he got to know at the Salk Institute, once told him, “What we lose in mystery we gain in awe,” and the phrase stuck with him.

“Our goal in some sense is to reduce the mystery, but that doesn’t reduce the awe,” he says. If scientists could produce a neural map that explains why chocolate ice cream tastes good, it would still taste just as good. The mystery would be gone, but the experience wouldn’t be diminished.

That leads Eagleman to make it clear he is a possibilian, not a mysterian (one who believes that there are things we humans can’t understand, problems we can’t solve). Eagleman acknowledges that in his lifetime we won’t come up with the theories to explain it all and that some of science’s stories may turn out to be wrong, but they usually are better than any alternative stories.

I poke a bit. Eagleman flies the possibilian flag, rejecting fundamentalism in religion, politics, economics. But might he be a technological fundamentalist – someone who believes that humans, using science, will always find high-energy/high-technology solutions to problems, including to the problems created by previous high-energy/high-technology processes and gadgets?

Eagleman certainly is upbeat about the possibility of finding significant ways to replace current sources of energy, for example. He believes that the more dire the problem, the more creative humans are; as we get closer to running out of oil, the incentive to solve the problem will pull us through.

Eagleman has confidence in the species, and confidence in himself. When I asked him about his admiration for the late astrophysicist Carl Sagan, he explained that he “would love to turn people on to the big ideas” the way Sagan did through books and the 1980 PBS series “Cosmos: A Personal Voyage.” Although he’s a boyish 38 years old, Eagleman doesn’t hesitate to acknowledge that he wants to carve out for himself that kind of special public place for himself as a scientist.

“Growing up, me and my parents, we never said ‘Someday you can be the president of the United States.’ We always felt like, ‘Someday you can be the next Carl Sagan.’ That was always the goal. That would be the apex for me.” Why such respect for Sagan? “He took the most beautiful ideas that we have in science and laid them out there in a way that any eighth-grader could understand, and that could bring tears to they eyes of any adult,” says Eagleman, noting that watching a DVD copy of “Cosmos” he recently bought had, indeed, brought tears to his eyes. [To watch the introduction to the series, go to http://www.youtube.com/watch?v=R7n71pm0K04.]

Beyond the joy of knowing about the world, there also are practical reasons we might want to deepen our understanding of how the brain constructs reality. Eagleman also works in the new interdisciplinary field called neurolaw, sorting through the implications of brain science for culpability, sentencing, and rehabilitation.

Imagine, for example, that Charles Whitman had not been shot dead in 1966 after he killed 14 people and wounded dozens with a rifle from the top of the Main Building at the University of Texas at Austin. What if the brain tumor found by an autopsy had instead been revealed by neuroimaging and it had been demonstrated the tumor caused his murderous rampage? If he had lived and gone to trial, should that have affected a legal determination of guilt? The type of sentence? The evaluation of when he might be paroled? Consider how controversial the existing insanity plea tends to be (recall John Hinckley, Jr.’s successful insanity plea after shooting Ronald Reagan) and it’s easy to imagine the ruckus that is ahead down this road. [To see a video of Eagleman speaking on “The Brain and The Law,” go to http://www.thersa.org/events/vision/vision-videos/david-eagleman-21-april-2009]

At the end of the pier

On these subjects, the confident Eagleman is on display, talking fast and then faster, offering elegant summaries of complex scientific theories and constructing analogies to explain the firing of our neurons. He hits roadblocks and thinks through solutions on the fly. Conversation with him is just plain fun.

But the more interesting side of Eagleman comes when he runs up against a truly troubling question, when he’s stopped cold by the overwhelming complexity of the world – both outside and inside us – and the limits of human intelligence. Instead of tossing off glib responses, he slows down and reveals the struggle inside Eagleman, between the confidence-bordering-on-hubris of a neuroscientist and the humility-that-produces-doubt of a writer who knows he’s chewing on age-old questions that won’t be solved in this or any other age.

In five hours of interviews, we ran into those walls a handful of times, most notably when I asked whether our big brains might mean we humans are a tragic species. Might our intellectual capacity to achieve great things contain the seeds of our own destruction? Given the multiple crises and threats, especially to the ability of the ecosystem to sustain life into even the near-term future, I ask, “Is the human story a tragic story?”

“That’s interesting. I would say …” he starts before pausing for 20 seconds, an eternity in Eagleman-time. He reframes the question: “Do we hit the solution or the disaster first?”

Here’s Eagleman’s upbeat answer: “My biggest place of hopefulness is in the fact that we’re leveraging human capital more than we’re ever done before. So I feel like that makes it even more likely for solutions to come along. I don’t mean to be a panglossian scientist and say that science progresses, it’s always going to lead to solutions, but yea, I …”

His voice trails off. Eagleman may be an upbeat possibilian, but he remains true to possibilianism. He repeats his confidence that we can meet challenges, but he knows the question can’t be dismissed. Being a serious possibilian is exciting, but it also can be scary. Are there any possibilities that scare Eagleman-the-scientist?

“I’ve been doing this for 18 years, and I sometimes feel like, oh my god, what if I’ve gone just a little too far? When you reach your arms down into it, sometimes I feel like I’m seeing the matrix in a sense. Oh my god, this is all a construction. So the same question that excites me [how does the brain construct reality?] can also scare the shit out of me a lot of times. Because it’s much more comfortable to imagine that you open your eyes and the world is full of color and things just exist and time flows like a river. But when you start breaking all that down and seeing that it’s a construction of the brain, it’s kind of awful, I guess because it makes you feel so alien to everything you’ve ever known and loved.”

Does that mean Eagleman-the-writer wants to believe that he has both a brain and a soul? How would he respond to the simple question, “Does David Eagleman have a soul?” He pauses again.

“So, I can answer that in two ways. I can tell you from my internal experience, and from my scientific training. Internally, I have felt as I’ve gotten older that I am not the same as my body, despite all of the neuroscience. How do I put this? What’s clear is that I depend entirely on the integrity of my body. As things in my brain change – if I were to develop a tumor, for example – that could completely change who I am, how I think. So I’m somehow yoked to my brain in a very strong way, and the question for all of us is, are we yoked to it 100 percent or is there some other little bit going on? From the inside, I have an intuition that I’m not just equivalent to my body. That said, intuitions always prove to be a very poor judge of reality. So, if you ask me, ‘do I have a soul?’ I would say ‘you know, I kind of feel like there’s something about me that’s a little separate from the biology.’ But I have no evidence for that.”

This struggle between the brain of a scientist and the soul of a writer continues in Eagleman. Maybe the brain allows itself to imagine a soul to take the sting out of mortality of the brain. Maybe the soul allows the brain to pretend to be in control, secure in the knowledge that the soul is immortal.

Hard to say, but in the space between the materialist and mystic, anything’s possible.